Glws I love my octo pulse 4s wide open grill so you don’t lose flow and they stop on a dime with any interruption so *if* a fish were to get in there I’m confident the blade would stop. My favorite mod is a hydros wave engine controller.It’s a WiFi enabled controller . Can be set up manually but if connected to WiFi it’s app driven. Will need to find an outside magnet to use on one . It fell into the nether regions of my rear chamber when I had a klutz moment taking things apart again from the tank